Communication apparatus, communications system, and communication method

ABSTRACT

A communication apparatus includes: a communication unit that periodically transmits, with an interval assigned by TDD (Time Division Duplex) being one TDD time slot and a plurality of TDD time slots being one period, a plurality of application packets corresponding to a plurality of serial signals generated by a plurality of applications to a communication partner device; and a transmission control unit that changes, for every one period, a priority of part of application packets corresponding to part of two or more applications of the plurality of applications, the part of application packets being transmitted in at least one specific TDD time slot for transmitting the part of application packets, the plurality of TDD time slots including the at least one specific TDD time slot.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Priority Patent ApplicationU.S. 63/153,536 filed Feb. 25, 2021, the entire contents of which areincorporated herein by reference.

BACKGROUND

The present disclosure relates to a communication apparatus, acommunications system, and a communication method.

A technology for performing high-speed serial communication between aMaster SerDes and a Slave SerDes has been proposed (see Japanese PatentApplication Laid-open No. 2011-239011).

When serial communication is performed between two SerDeses, in the casewhere there is a large difference between the amount of data to betransmitted from one SerDes to the other SerDes and the amount of datato be transmitted from the other SerDes to the one SerDes, it isconceivable to adopt a TDD (Time Division Duplex) method to make thedata transmission capacity different in the uplink direction and thedownlink direction. The TDD method is a half-duplex communication methodin which the communication in the uplink direction and the communicationin the downlink direction cannot be performed at the same time and onlycommunication in one direction can be performed.

SUMMARY

There is not only one serial communication standard, and there arevarious standards such as SPI (Serial Peripheral Interface), GPIO(General Purpose Input/Output), and I2C (Inter-Integrated Circuit). Inthe case where a plurality of types of serial signals of these differentstandards is transmitted/received between two SerDes using the TDDmethod, it is necessary to convert the serial signal of each standardinto a packet conforming to the TDD method.

In the TDD method, a packet including a serial signal istransmitted/received in units of TDD time slots in some cases. In orderto transmit/receive a plurality of types of serial signals of differentstandards, it is conceivable to generate a plurality of packets eachincluding a plurality of types of serial signals, assign each packet toa different TDD time slot, and transmit the packet.

However, there is a problem that the transmission latency increases ifthe assignment of the TDD time slot is not optimized, because aplurality of types of serial signals of different standards hasdifferent transmission frequencies and different signal amounts for eachtype of serial signal. In particular, when a TDD time slot is assignedin a constant period to a packet including a serial signal having a lowtransmission frequency, there is a possibility that there is no packetto be transmitted in the assigned TDD time slot. Further, there is apossibility that when a TDD time slot is assigned to a packet includinga serial signal having a low transmission frequency, the timing oftransmitting a packet including a serial signal having a hightransmission frequency is delayed, thereby increasing the transmissionlatency.

In this regard, in the present disclosure, there is provided acommunication apparatus, a communications system, and a communicationmethod that are capable of improving transmission efficiency whileminimizing the transmission latency.

Solution to Problem

In accordance with an embodiment of the present disclosure, there isprovided a communication apparatus including:

a communication unit that periodically transmits, with an intervalassigned by TDD (Time Division Duplex) being one TDD time slot and aplurality of TDD time slots being one period, a plurality of applicationpackets corresponding to a plurality of serial signals generated by aplurality of applications to a communication partner device; and atransmission control unit that changes, for every one period, a priorityof part of application packets corresponding to part of two or moreapplications of the plurality of applications, the part of applicationpackets being transmitted in at least one specific TDD time slot fortransmitting the part of application packets, the plurality of TDD timeslots including the at least one specific TDD time slot.

The transmission control unit may change, for every one period, thepriority of the part of application packets in a preset order or inaccordance with user's designation.

The transmission control unit may change, for every one period, thepriority of the part of application packets to be transmitted in thespecific TDD time slot in order.

The transmission control unit may preferentially transmit a packetcorresponding to an application having a higher priority in the specificTDD time slot.

The transmission control unit may check whether an application having ahigher priority has prepared a packet to be transmitted in the specificTDD time slot, and check, if not prepared, whether or not an applicationhaving the next highest priority has prepared a packet to be transmittedin the specific TDD time slot.

The transmission control unit may repeat processing of checking whetheror not a packet to be transmitted is prepared in descending order ofpriority until a packet that can be transmitted in the specific TDD timeslot is found.

The transmission control unit may stop, where none of the part ofapplications have prepared a packet to be transmitted in the specificTDD time slot, transmitting a valid packet in the specific TDD timeslot.

The transmission control unit may cause the one period to include adedicated TDD time slot for transmitting a packet including a serialsignal generated by an application designated in advance separately fromthe specific TDD time slot.

The application designated in advance may be an application other thanthe part of applications of the plurality of applications.

The transmission control unit may increase the number of dedicated TDDtime slots included in the plurality of periods to be larger than thenumber of specific TDD time slots.

The part of applications may include at least one of an application thatgenerates a packet of I2C (Inter-Integrated Circuit) communication or anapplication that generates a packet of GPIO (General PurposeInput/Output) communication, and the application designated in advancemay include at least one of an application that generates a packet ofSPI (Serial Peripheral Interface) communication or an application thatgenerates a packet of OAM (Operation, Administration, Maintenance).

The transmission control unit may change, for every one period, thepriority of the part of applications by one level, and make, where thepriority has reached the lowest or the highest, the priority the highestor the lowest in the next period.

The transmission control unit may set, on the basis of at least one of atransmission frequency or a signal amount of a serial signal generatedby each of the plurality of applications, whether to assign thededicated TDD time slot to the corresponding application or share thespecific TDD time slot with another application.

The communication apparatus may further include:

a plurality of encapsulators that is provided for each of the pluralityof applications, generates a packet including a serial signal generatedby the corresponding application, and outputs a ready signal indicatingwhether or not the packet has been generated; and

a frame construction unit that generates, on the basis of a plurality ofpackets generated by the plurality of encapsulators, a link frame to betransmitted to the communication partner device in the one period, inwhich

the frame construction unit may include a scheduler that manages thepriority of the specific TDD time slot and determines, on the basis oftwo or more ready signals generated by two or more encapsulatorscorresponding to the part of applications, the application thattransmits a packet in the specific TDD time slot.

The frame construction unit may include

a plurality of container makers that generates a container including acontainer payload and a container header, the container payloadincluding a packet generated by each of the plurality of encapsulators,and

a multiplexer that selects, under control of the scheduler, a pluralityof containers generated by the plurality of container makers one by oneto generate the link frame.

The number of the plurality of container makers may be the same as thenumber of TDD time slots in the one period.

The communication apparatus may further include:

a plurality of encapsulators that is provided for each of the pluralityof applications, generates a packet including a serial signal generatedby the corresponding application, and outputs a ready signal indicatingwhether or not the packet has been generated;

-   -   a packet selection unit that manages the priority of the        specific TDD time slot and selects, on the basis of two or more        ready signals generated by two or more encapsulators        corresponding to the part of applications, a packet to be        transmitted in the specific TDD time slot from two or more        packets generated by the two or more encapsulators; and

a frame construction unit that generates, on the basis of the packetselected by the packet selection unit and a packet corresponding to anapplication other than the part of applications of the plurality ofapplications, a link frame to be transmitted to the communicationpartner device in the one period, in which

the frame construction unit may include a scheduler that manages apacket to be transmitted in the plurality of TDD time slots in the oneperiod.

The frame construction unit may include

a plurality of container makers that generates a container including acontainer payload and a container header corresponding to the containerpayload, the container payload including a packet selected by the packetselection unit and a packet corresponding to an application other thanthe part of applications of the plurality of applications, and

a multiplexer that selects, under control of the scheduler, a pluralityof containers generated by the plurality of container makers one by oneto generate the link frame.

The number of the plurality of container makers may be less than thenumber of TDD time slots in the one period.

In accordance with an embodiment of the present disclosure, there isprovided a communications system including: a first communicationapparatus that transmits/and receives a packet by TDD (Time DivisionDuplex) via a predetermined communication protocol; and a secondcommunication apparatus, in which

the first communication apparatus includes

-   -   a communication unit that periodically transmits, with an        interval assigned by TDD (Time Division Duplex) being one TDD        time slot and a plurality of TDD time slots being one period, a        plurality of application packets corresponding to a plurality of        serial signals generated by a plurality of applications to a        communication partner device, and    -   a transmission control unit that changes, for every one period,        a priority of part of application packets corresponding to part        of two or more applications of the plurality of applications,        the part of application packets being transmitted in at least        one specific TDD time slot for transmitting the part of        application packets, the plurality of TDD time slots including        the at least one specific TDD time slot, and

the second communication apparatus includes a second communication unitthat receives a packet transmitted from the first communicationapparatus and periodically transmits a packet to the first communicationapparatus with the plurality of TDD time slots being the one period.

In accordance with the present disclosure, there is provided acommunication method including:

periodically transmitting, with an interval assigned by TDD (TimeDivision Duplex) being one TDD time slot and a plurality of TDD timeslots being one period, a plurality of application packets correspondingto a plurality of serial signals generated by a plurality ofapplications to a communication partner device; and

changing, for every one period, a priority of part of applicationpackets corresponding to part of two or more applications of theplurality of applications, the part of application packets beingtransmitted in at least one specific TDD time slot for transmitting thepart of application packets, the plurality of TDD time slots includingthe at least one specific TDD time slot.

These and other objects, features and advantages of the presentdisclosure will become more apparent in light of the following detaileddescription of best mode embodiments thereof, as illustrated in theaccompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing a schematic configuration of acommunications system;

FIG. 2 is a block diagram of a communications system embodying theinternal configuration of a SerDes;

FIG. 3 is a diagram showing a configuration of a link frame and atransmission symbol transmitted by a PHY unit;

FIG. 4 is a block diagram showing an internal configuration of a frameconstruction unit in the SerDes in FIG. 2;

FIG. 5 is a diagram showing a transmission timing of the SerDes in FIG.2;

FIG. 6 is a diagram showing a transmission timing in the case where anI2C signal has been input from an ECU to the SerDes.

FIG. 7 is a block diagram of a frame construction unit according to afirst embodiment of the present disclosure;

FIG. 8 is a flowchart showing a processing operation of a scheduler inFIG. 7;

FIG. 9 is a diagram showing a transmission timing in an UP Linkaccording to this embodiment; and

FIG. 10 is a block diagram showing a configuration of a frameconstruction unit and the surroundings thereof according to a secondembodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, a communication apparatus, a communications system, and acommunication method according to embodiments of the present disclosurewill be described with reference to the drawings. Although maincomponents of the communication apparatus and the communications systemwill be mainly described below, the communication apparatus and thecommunications system may have components and functions not shown ordescribed. The following description does not exclude the components orfunctions not shown or described.

A communications system according to an embodiment of the presentdisclosure performs serial communication between two SerDeses. FIG. 1 isa block diagram showing a schematic configuration of a communicationssystem 1 including two SerDeses, i.e., a SerDes 200 (SerDes #1) and aSerDes 400 (SerDes #2). FIG. 1 shows an example in which the SerDes 200and the SerDes 400 perform serial communication with each other. TheSerDes 200 and the SerDes 400, which are high-speed serial interfacedevices, are connected to each other by a cable 300 having the length ofseveral to ten and several meters. An ECU 100 is connected to the SerDes200, and a peripheral device 500 (Peripheral #1) and a peripheral device600 (Peripheral #2) are connected to the SerDes 400. The ECU 100performs processing of receiving main data such as a video signal andtransmitting the received data, and transmits/receives an SPI (SerialPeripheral Interface) signal, an I2C (Inter-Integrated Circuit) signal,a GPIO (general purpose IO) signal, or the like to control the wholesystem.

Meanwhile, the peripheral device 500 connected to the SerDes 400transmits high-speed and large-capacity main data such as a videosignal, and transmits/receives a control signal by SPI or GPIO. Further,the peripheral device 600 connected to the SerDes 400 transmits/receivesa low-speed signal such as observation data and a control signal by I2Cor GPIO.

The communications system including the two SerDeses 200 and 400 shownin FIG. 1 is provided in various apparatuses such as an in-vehiclecamera module. As an interface technology for serial communicationbetween the two SerDeses 200 and 400, FPD-LINK has been known. Inaddition, in a high-speed serial interface standard organization,Automotive SerDes Alliance (ASA), the standardization work of ahigh-speed serial interface technology for automobiles is currently inprogress. The difference between FPD-LINK and ASA is that ASA uses TimeDivision Duplex (TDD) while FPD-LINK uses Frequency Division Duplex(FDD) as a method for realizing two-way communication.

The packet transmission timing and the frequency band of FDD areillustrated in the lower left of FIG. 1, and the packet transmissiontiming and the frequency band of ASA are illustrated in the lower rightof FIG. 1. In FDD, a Down Link and an UP Link use difference frequencybands to transmit/receive packets in parallel during an overlappingperiod. Meanwhile, in TDD, a Down Link and an UP Link use an overlappingfrequency band to transmit/receive packets in time division.

FIG. 2 is a block diagram of the communications system 1 embodying theinternal configuration of the SerDeses 200 and 400. FIG. 2 shows anexample in which an application includes an SPI signal, an I2C signal,and a GPIO signal. As shown in FIG. 2, the SerDes 200 includes a PHYunit (PHY block) 200-1, a LINK unit (LINK block) 200-2, a plurality ofencapsulators (Application Stream Encapsulators) 200-3, a plurality ofde-encapsulators (Application Stream De-encapsulators) 200-4, and acontrol register (Control registers) 200-5. The PHY unit 200-1 includesan UP Link transmission unit (UP Link Tx) 200-1-1 and a Down Linktransmission unit (Down Link Rx) 200-1-2. The LINK unit 200-2 includes aframe construction unit (Frame Constructor) 200-2-1, a framedeconstruction unit (Frame De-constructor) 200-2-2, and an OAM(Operation Administration Maintenance) unit 200-2-3.

The ECU 100 generates an SPI signal, an I2C signal, and a GPIO signal,which are control signals, as necessary for processing, and outputs thegenerated signal to the SerDes 200. The plurality of encapsulators 200-3in the SerDes 200 is provided for each application (e.g., each of theSPI signal, the I2C signal, and the GPIO signal). Each of theencapsulators 200-3 generates a corresponding application packet.

The encapsulator 200-3 for an SPI signal receives an SPI signal from theECU 100 and generates an application packet including the SPI signal.The encapsulator 200-3 for an I2C signal receives an I2C signal from theECU 100 and generates an application packet including the I2C signal.The encapsulator 200-3 for a GPIO signal receives a GPIO signal from theECU 100 and generates an application packet including the GPIO signal.

The plurality of de-encapsulators 200-4 in the SerDes 200 is providedfor each application. The de-encapsulator 200-4 for main data restoresmain data from the received application packet and transmits therestored main data to the ECU 100. The de-encapsulator 200-4 for an SPIsignal restores an SPI signal from the received application packet andtransmits the restored SPI signal to the ECU 100. The de-encapsulator200-4 for an I2C signal restores an I2C signal from the receivedapplication packet and transmits the restored I2C signal to the ECU 100.The de-encapsulator 200-4 for a GPIO signal restores a GPIO signal fromthe received application packet and transmits the restored GPIO signalto the ECU 100.

FIG. 3 is a diagram showing a configuration of an application packetgenerated by the plurality of encapsulators 200-3, a link framegenerated by the LINK unit 200-2, and a transmission symbol to betransmitted by the PHY unit 200-1. As shown in Part (3-1) of FIG. 3, theapplication packet includes a packet header and application packet data.

The LINK unit 200-2 generates a container for each of the plurality ofencapsulators 200-3, and generates a link frame including a plurality ofcontainers. As shown in Part (3-2) of FIG. 3, the container includes acontainer header and a container payload. The container header includesaddress information of a device on the reception side supplied from thecontrol register 200-5 and address information of the de-encapsulator200-4.

The link frame generated by the LINK unit 200-2 is supplied to the UPLink transmission unit 200-1-1 of the PHY unit 200-1. The UP Linktransmission unit 200-1-1 adds a sync header that is necessary forsynchronization processing on the reception side to the link frame((3-3) in FIG. 3) to generate a transmission frame ((3-4) in FIG. 3),and then performs modulation processing such as binary transmission(NRZ) and quadrature transmission (PAM4) to convert the transmissionframe into a transmission symbol ((3-5) in FIG. 3) and outputs theobtained transmission symbol to the cable 300. This is the transmissionprocessing on the UP Link side.

One transmission frame ((3-4) in FIG. 3) is transmitted within one TDDtime slot of a TDD method. In the TDD method, Down Link transmission andUP Link transmission are performed once at different timings within oneTDD burst period. The above-mentioned transmission frame is transmittedwithin, for example, a Down Link transmission period. For example, inthe case where the UP Link transmits only a control signal and the DownLink transmits a video signal including a control signal, or the like,the Down Link basically occupies a larger amount of time and the timeratio is 1: several tens.

FIG. 4 is a block diagram showing the internal configuration of theframe construction unit 200-2-1 in the SerDes 200 in FIG. 2. The frameconstruction unit 200-2-1 includes a plurality of container makers(container makers) 200-2-1-1 corresponding to the plurality ofencapsulators 200-3, a multiplexer 200-2-1-3, and a scheduler 200-2-1-2.Each of the encapsulators 200-3 includes a packet maker (Packet maker)200-3-1 and a buffer 200-3-3. The application packet generated by thepacket maker 200-3-1 is once stored in the buffer 200-3-3 and then inputto the corresponding container maker 200-2-1-1 in the frame constructionunit 200-2-1 in accordance with an instruction from the scheduler200-2-1-2.

Each of the container makers 200-2-1-1 receives a correspondingapplication packet from the corresponding encapsulator 200-3 or the OAMunit 200-2-3 to generate a corresponding container. The containergenerated by each of the container makers 200-2-1-1 is input to themultiplexer 200-2-1-3. The scheduler 200-2-1-2 outputs a timingadjustment signal indicating at which timing each container is output.The multiplexer 200-2-1-3 generates a link frame including a pluralityof containers on the basis of the timing adjustment signal from thescheduler 200-2-1-2.

At system startup, a schedule according to the transmission bandrequired by an application to be transmitted by the ECU 100 istransferred to the control register 200-5 by some means not shown inFIG. 2. The control register 200-5 supplies the schedule to thescheduler 200-2-1-2. Therefore, control is performed such that thecontainer for transmitting wideband information such as a video signalis selected more often by the multiplexer 200-2-1-3 per unit time and alow-speed signal such as GPIO is selected less often.

Similarly, an OAM signal including the schedule generated by the ECU 100is supplied also to the scheduler in a frame construction unit 400-2-1of the SerDes 400 via the UP Link.

Next, the reception processing on the UP Link side of the SerDes 400will be described. As shown in FIG. 2, the SerDes 400 includes a PHYunit (PHY block) 400-1, a LINK unit (LINK block) 400-2, a plurality ofencapsulators (Application Stream Encapsulator) 400-3, a plurality ofde-encapsulators (Application Stream De-encapsulator) 400-4, and acontrol register (Control registers) 400-5. The PHY unit 400-1 includesa Down Link transmission unit (Down Link Tx) 400-1-1 and an UP Linkreception unit (UP Link Rx) 400-1-2. The LINK unit 400-2 includes aframe construction unit 400-2-1, a frame deconstruction unit 400-2-2,and an OAM unit 400-2-3.

The encapsulator 400-3 for main data receives main data from theperipheral device 500 and generates an application packet including themain data. The encapsulator 400-3 for an SPI signal receives an SPIsignal from the peripheral device 500 and generates an applicationpacket including the SPI signal. The encapsulator 400-3 for a GPIOsignal receives a GPIO signal from the peripheral device 500 andgenerates an application packet including the GPIO signal. Thede-encapsulator 400-4 for an I2C signal restores an I2C signal from thereceived packet and transmits the restored I2C signal to the peripheraldevice 600. The de-encapsulator 400-4 for a GPIO signal restores a GPIOsignal from the received packet and transmits the restored GPIO signalto the peripheral device 600.

The SerDes 400 generates a lock synchronized with a symbol frequencywith the sync signal added to the top of the transmission symbol ((3-5)in FIG. 3) received from the SerDes 200 to reproduce the transmissionframe ((3-4) in FIG. 3). The sync header is removed from the reproducedtransmission frame ((3-4) in FIG. 3) to generate the link frame ((3-3)in FIG. 3) and the generated link frame is input to the framedeconstruction unit 400-2-2 in the LINK unit 400-2.

The frame deconstruction unit 400-2-2 divides the link frame ((3-3) inFIG. 3) into containers ((3-2) in FIG. 3), acquires address informationof the de-encapsulator 400-4 from the container header of eachcontainer, and outputs, to the corresponding de-encapsulator 400-4, theapplication packet ((3-1) in FIG. 3) included in the container payloadof the container.

Each of the de-encapsulators 400-4 reconstructs, on the basis of thepacket header in the corresponding application packet, the applicationpacket data in the application packet into the format of eachapplication and outputs the obtained data to the correspondingperipheral device 500 or 600.

Since the processing on the Down Link side in which information istransmitted from the peripheral device 500 or 600 to the ECU 100 issimilar to the processing on the UP Link side, description thereof isomitted.

In the ASA standard of a TDD method, the number of times per unit timeand the transmission order for transmitting a container ((3-2) in FIG.3) that stores each application to be transmitted are determined inadvance at the time of system design. As a result, the latency for eachapplication becomes substantially constant and problems such astransmission jitter of an application are avoided. This is veryconvenient in the case where large-capacity data such as a video signalis constantly transmitted. Meanwhile, the transmission band required byeach of an SPI signal, an I2C signal, and a GPIO signal for mainlycontrolling a peripheral device may be narrower than that of the videosignal.

FIG. 5 is a diagram showing the transmission timing of the SerDes 200 inFIG. 2. FIG. 5 shows an example in which the frame construction unit200-2-1 on the UP Link side sets the transmission schedule of eachapplication packet With 6 TDD time slots as one period. As shown in FIG.5, the time of one switching between the Down Link and the UP Link isthe transmission time unit of TDD (1 TDD burst period=1 TDD time slot).In the example of FIG. 5, one application packet is transmitted for eachTDD time slot in the UP Link ((5-1) in FIG. 5). In this case, theapplication packet including an OAM signal is transmitted once every 6TDD time slots, an application packet including an SPI signal istransmitted four times every 6 TDD time slots, and an application packetincluding a GPIO signal and an application packet including an I2Csignal are transmitted once every 12 TDD time slots ((5-2) in FIG. 5).

As shown in FIG. 2 to FIG. 4, the SPI signal, the I2C signal, and theGPIO signal to be input to the SerDes 200 are once input to theencapsulator 200-3, converted into a corresponding application packet,and then, buffered and input to the frame construction unit 200-2-1 inaccordance with the read timing of the scheduler 200-2-1-2. The readtiming determined by the scheduler 200-2-1-2 coincides with thetransmission schedule of each application shown in Parts (5-1) and (5-2)of FIG. 5. For example, application packets SPI #m and #m+1 of an SPIsignal are respectively transmitted in TDD time slots #9 and #10 ((5-3)in FIG. 5), and application packets GPI #n and #n+1 of a GPIO signal((5-5) in FIG. 5) are respectively transmitted in TDD time slots #14 and#26 ((5-2) in FIG. 5).

However, since the I2C signal is in an adle state at this time point((5-8) in FIG. 5), there is no need to transmit an application packet ofan I2C signal ((5-8) in FIG. 5).

FIG. 6 is a diagram showing the transmission timing in the case where anI2C signal has been input from the ECU 100 to the SerDes 200. In thecase of FIG. 6, an application packet of an I2C signal is transmitted ina TDD time slot #20.

Now, assumption is made that a signal such as an interrupt signal, whichrequires a small transmission band but whose change in the signal statecannot be predicted in advance is transmitted using a GPIO signal. Asshown in FIG. 5, assumption is made that since the band required fortransmitting a GPIO signal is small, TDD time slots are assigned suchthat the GPIO signal is transmitted once every 12 TDD time slots. Inthis case, the change in the GPI signal ((5-6) in FIG. 5) input from theECU 100 is sampled at intervals of 12 TDD time slots and converted intopackets GPI #n and #n+1 ((5-5) in FIG. 5) of a GPIO signal, and thepackets are respectively transmitted in TDD time slots #14 and #26((5-2) in FIG. 5).

The change in the GPI signal ((5-6) in FIG. 5) input from the ECU 100has occurred near TDD time slots #2 to #3, but the timing at which thischange is packetized and transmitted is a TDD time slot #26, whichcauses transmission latency. For example, in the case where 1 TDD burstperiod is approximately 30 usec, transmission latency of approximately690 usec occurs.

In order to reduce the transmission latency of an application, it onlyneeds to increase the frequency of assigning a TDD time slot to theapplication. However, since the application does not constantly transmita signal and transmits a signal only as necessary, the efficiency ofusing the TDD time slot deteriorates in the case where the requiredtransmission band is small.

In this regard, the communication apparatus and the communicationssystem according to the embodiment of the present disclosure arecharacterized in that the transmission efficiency is improved whileminimizing the transmission latency when transmitting, by a TDDtransmission method, a plurality of applications to which a transmissionschedule has been assigned in advance.

First Embodiment

FIG. 7 is a block diagram of the frame construction unit 200-2-1according to a first embodiment of the present disclosure. In FIG. 7,components common to those of the frame construction unit 200-2-1 inFIG. 4 are denoted by the same reference symbols, and the differenceswill be mainly described below. Similarly to FIG. 4, the frameconstruction unit 200-2-1 in FIG. 7 includes a plurality of containermakers (container makers) 200-2-1-1 corresponding to the plurality ofencapsulators 200-3, the multiplexer 200-2-1-3, and a scheduler200-2-1-4.

In the frame construction unit 200-2-1 in FIG. 7, the operation of thescheduler 200-2-1-4 is different from the scheduler 200-2-1-4 in FIG. 4.Further, each of the encapsulators 200-3 shown in FIG. 7 stores, in thecorresponding buffer 200-3-3, an application packet generated by thecorresponding packet maker 200-3-1, and then outputs a data readysignal. The data ready signal is a signal indicating that a validapplication packet is stored in the corresponding buffer 200-3-3. Thedata ready signal from each of the encapsulators 200-3 is input to thescheduler 200-2-1-4. The scheduler 200-2-1-4 controls, on the basis ofthe data ready signal from each of the encapsulators 200-3, the order ofcausing the container generated by each of the container makers200-2-1-1 to be included in the transmission frame.

FIG. 8 is a flowchart showing the processing operation of the scheduler200-2-1-4 in FIG. 7. FIG. 9 is a diagram showing the transmission timingin the UP Link according to this embodiment. Hereinafter, the processingoperation of the communication apparatus and the communications systemaccording to this embodiment will be described on the basis of FIG. 7 toFIG. 9.

Similarly to the scheduler 200-2-1-2 in FIG. 4, the scheduler 200-2-1-4in FIG. 7 determines in advance, before the communications system startstransmission, which application packet is assigned to which TDD timeslot and transmitted by the schedule management from the ECU 100 via thecontrol register 200-5.

The ECU 100 or the control register 200-5 prepares a specific TDD timeslot (shared time slot) in the scheduler 200-2-1-4, and assigns, to theshared time slot, not one application packet but a plurality ofapplication packets. A signal such as a control signal, which has arelatively small transmission band and a low transmission frequency, isassigned to this application packet transmitted in the specific sharedtime slot.

Further, the ECU 100 or the control register 200-5 sets, for thescheduler 200-2-1-4, the output priority of the application packetassigned to the shared time slot. How many shared time slots areprepared, which application packet is assigned, and how the priority isset are changed in accordance with the system and the operationsituation. The priority may be determined at the time of system design,for example. That is, the order in which the priority is periodicallychanged may be determined at the time of system design and stored in amemory, a resister, or the like (not shown).

Alternatively, a user may set the priority or the order in which thepriority is changed using a, updatable value of a resister. In thiscase, the user can change the priority or the order in which thepriority is changed by updating the value of the resister at anappropriate timing.

The scheduler 200-2-1-4 determines whether or not the TDD time slot tobe scheduled is the shared time slot (Step S1). For example, TDD timeslots #2, #8, #14, #20, and #26 in FIG. 9 are determined to be theshared time slots.

In the case of the shared time slot, whether or not the applicationpacket having the highest priority is stored in the corresponding buffer200-3-3 is determined by the data ready signal (Step S2). In the casewhere the application packet having the highest priority is stored inthe buffer 200-3-3, it is determined that the application packet hasbeen prepared, a container is generated by the container maker 200-2-1-1corresponding to the application packet stored in the buffer 200-3-3,and the generated container is selected by the multiplexer 200-2-1-3 toform a link frame (Step S3).

After that, the priority of the shared time slot is changed by one level(Step S4). For example, in the case where there are application packetsA, B, and C, the priority of each of five shared time slots #2, #8, #14,#20, and #26 in FIG. 9 is changed as follows. Note that the following isjust an example, and the order in which the priority is changed isarbitrary.

Priority of shared time slot #2: A->B->C

Priority of shared time slot #8: B->C->A

Priority of shared time slot #14: C->A->B

Priority of shared time slot #20: A->B->C

Priority of shared time slot #26: B->C->A

When the processing of Step S4 in FIG. 8 is finished, the processing ofStep S1 and subsequent Steps is repeated. More specifically, forexample, in FIG. 9, the priority of the TDD time slot #2 satisfies therelationship of GPIO>I2C, the priority of the next TDD time slot #8satisfies the relationship of I2C>GPIO, and the priority of the next TDDtime slot #14 satisfies the relationship of GPIO>I2C similarly to theoriginal. As a result, it is possible to guarantee the transmission bandoriginally assigned to the application packet. As described above, thepriority of the shared time slot is switched in order for every oneperiod.

When it is determined in Step S2 that the application packet is notstored in the buffer 200-3-3, whether or not there is an applicationpacket having the next highest priority is determined (Step S5). When itis determined that there is an application packet having the nexthighest priority, whether or not the determined application packet isstored in the corresponding buffer 200-3-3 is determined by the dataready signal (Step S6). When it is determined that the determinedapplication packet is stored in the corresponding buffer 200-3-3, theprocessing proceeds to Step S3. For example, although the applicationpacket including an I2C signal has the highest priority in the TDD timeslot #8 in FIG. 9, the I2C signal is null at this time point and theapplication packet including an I2C signal is not stored in thecorresponding buffer 200-3-3. For this reason, the determination in StepS2 in FIG. 8 is NO, the processing proceeds to Step S5, and whether ornot there is an application packet having the next highest priority isdetermined. In the TDD time slot #8 in FIG. 9, the GPIO signal has thenext highest priority of the I2C signal. At this time point, theapplication packet including a GPIO signal is stored in thecorresponding buffer 200-3-3 (GPI# n+1 Part 9-5 of FIG. 9). In thisregard, the container maker 200-2-1-1 corresponding to this applicationpacket generates a container including this application packet.

Meanwhile, in the case where it is determined in Step S5 that there isno application packet having the next highest priority, the processingproceeds to Step S4. For example, in the TDD time slot #14 in FIG. 9,the application packet including a GPIO signal has the highest priority.At this time point, an application to be transmitted is not stored inthe buffer 200-3-3 in the encapsulator 200-3 for a GPIO signal. For thisreason, the determination is NO in Step S2 in FIG. 8, the processingproceeds to Step S5, and whether or not there is an application packethaving the next highest priority is determined. In the TDD time slot #14in FIG. 9, the I2C signal has the next highest priority. At this timepoint, the I2C signal is null and a valid application packet is notstored in the corresponding buffer 200-3-3. For this reason, thedetermination is NO in Step S5, and the priority of the shared time slotis switched in Step S4.

When it is determined in Step S1 that the TDD time slot to be scheduledis not the shared time slot, the scheduler 200-2-1-4 selects thedesignated application packet, a container corresponding to the selectedapplication packet is generated by the container maker 200-2-1-1, andthe generated container is selected by the multiplexer 200-2-1-3 to forma link frame (Step S7). When the processing of Step S7 is finished, theprocessing of Step S1 and subsequent Steps is repeated.

As described above, in the first embodiment, when serial transmission isperformed by a TDD method, one period including a plurality of TDD timeslots includes a shared time slot capable of transmitting a packetincluding one of a plurality of types of serial signals. Since aplurality of types of application packets each including an applicationsignal having a low transmission frequency is transmitted in the sharedtime slot and the priority when transmitting the plurality of types ofapplication packets in the shared time slot is changed in order, it ispossible to transmit the plurality of types of application packets withequal transmission latency. Further, by transmitting a plurality oftypes of application packet each having a low transmission frequency inthe shared time slot, it is possible to increase the number of TDD timeslots to be assigned to the application packet having a hightransmission frequency and further reduce the transmission latency ofthe application packet having a high transmission frequency. Therefore,in accordance with this embodiment, it is possible to efficientlytransmit a plurality of types of serial signals corresponding to aplurality of applications by a TDD method.

Second Embodiment

A second embodiment is different from the first embodiment in theconfiguration of the frame construction unit 200-2-1 in the LINK unit200-2 and the surroundings thereof.

FIG. 10 is a block diagram showing a configuration of the frameconstruction unit 200-2-1 according to the second embodiment and thesurroundings thereof. In the second embodiment, a packet selector 200-6is disposed between the plurality of encapsulators 200-3 and the frameconstruction unit 200-2-1.

The packet selector 200-6 executes part of functions of the scheduler200-2-1-4 in FIG. 7. Specifically, the packet selector 200-6 isconnected to two or more encapsulators 200-3 each transmitting anapplication packet in the shared time slot. Each of the two or moreencapsulators 200-3 connected to the packet selector 200-6 includes thepacket maker 200-3-1 and the buffer 200-3-3. Each of the encapsulators200-3 outputs the data ready signal when an application packet is storedin the corresponding buffer 200-3-3. The data ready signal is input tothe packet selector 200-6.

The packet selector 200-6 selects, on the basis of the data ready signalfrom the two or more encapsulators 200-3 each transmitting anapplication packet in the shared time slot, an application packet to betransmitted in the shared time slot. The data ready signal is a signalindicating that the corresponding application packet is stored in thecorresponding buffer 200-3-3, and is output from the correspondingencapsulator 200-3. The application packet transmitted in the sharedtime slot is input to the frame construction unit 200-2-1.

Similarly to FIG. 7, the frame construction unit 200-2-1 in FIG. 10includes a plurality of container makers 200-2-1-1 (Container makers)corresponding to the plurality of encapsulators 200-3 or the OAM unit200-2-3, the multiplexer 200-2-1-3, and the scheduler 200-2-1-5. Thescheduler 200-2-1-5 in FIG. 10 is different from the scheduler 200-2-1-4in FIG. 7.

Although the frame construction unit 200-2-1 in FIG. 7 includes the samenumber of the container makers 200-2-1-1 as the plurality ofencapsulators 200-3, the frame construction unit 200-2-1 in FIG. 10includes the container makers 200-2-1-1 whose number is smaller thanthat of the plurality of encapsulators 200-3. More specifically, one ofa plurality of application packets to be transmitted in the shared timeslot is selected by the packet selector 200-6, and the selectedapplication packet is input to the dedicated container maker 200-2-1-1.

A read timing signal informing the timing of the shared time slot isinput from the scheduler 200-2-1-5 to the packet selector 200-6. Thepacket selector 200-6 performs, when a read timing signal is input, theprocessing operation similar to that in the flowchart shown in FIG. 8.The packet selector 200-6 transmits, when selecting an applicationpacket to be transmitted in the shared time slot, the application packetto the corresponding container maker 200-2-1-1 together with packetinformation indicating which application the application corresponds to.The corresponding container maker 200-2-1-1 generates, on the basis ofthe received packet information, a container header together with acontainer payload including the received application packet to completea container.

The scheduler 200-2-1-5 in the frame construction unit 200-2-1 selects,setting information of the control register 200-5, a plurality ofcontainers generated by the plurality of container makers 200-2-1-1 oneby one to generate a link frame.

As described above, in the second embodiment, since the packet selector200-6 is provided between the plurality of encapsulators 200-3 and theframe construction unit 200-2-1 to select an application packet to betransmitted in the shared time slot, it is possible to reduce the numberof the container makers 200-2-1-1 in the frame construction unit200-2-1. Further, since the packet selector 200-6 performs part of theprocessing of schedule management of the scheduler 200-2-1-5, it ispossible to reduce the processing load of the scheduler 200-2-1-5 andsimplify the internal configuration of the frame construction unit200-2-1.

Note that the present technology may also take the followingconfigurations.

(1) A communication apparatus, including:

a communication unit that periodically transmits, with an intervalassigned by TDD (Time Division Duplex) being one TDD time slot and aplurality of TDD time slots being one period, a plurality of applicationpackets corresponding to a plurality of serial signals generated by aplurality of applications to a communication partner device; and atransmission control unit that changes, for every one period, a priorityof part of application packets corresponding to part of two or moreapplications of the plurality of applications, the part of applicationpackets being transmitted in at least one specific TDD time slot fortransmitting the part of application packets, the plurality of TDD timeslots including the at least one specific TDD time slot.

(2) The communication apparatus according to (1), in which thetransmission control unit changes, for every one period, the priority ofthe part of application packets in a preset order or in accordance withuser's designation.(3) The communication apparatus according to (1), in which thetransmission control unit changes, for every one period, the priority ofthe part of application packets to be transmitted in the specific TDDtime slot in order.(4) The communication apparatus according to (1), in which thetransmission control unit preferentially transmits a packetcorresponding to an application having a higher priority in the specificTDD time slot.(5) The communication apparatus according to any one of (1) to (4), inwhich

the transmission control unit checks whether an application having ahigher priority has prepared a packet to be transmitted in the specificTDD time slot, and checks, if not prepared, whether or not anapplication having the next highest priority has prepared a packet to betransmitted in the specific TDD time slot.

(6) The communication apparatus according to (5), in which

the transmission control unit repeats processing of checking whether ornot a packet to be transmitted is prepared in descending order ofpriority until a packet that can be transmitted in the specific TDD timeslot is found.

(7) The communication apparatus according to any one of (1) to (6), inwhich

the transmission control unit stops, where none of the part ofapplications have prepared a packet to be transmitted in the specificTDD time slot, transmitting a valid packet in the specific TDD timeslot.

(8) The communication apparatus according to any one of (1) to (7), inwhich

the transmission control unit causes the one period to include adedicated TDD time slot for transmitting a packet including a serialsignal generated by an application designated in advance separately fromthe specific TDD time slot.

(9) The communication apparatus according to (8), in which

the application designated in advance is an application other than thepart of applications of the plurality of applications.

(10) The communication apparatus according to (8) or (9), in which

the transmission control unit increases the number of dedicated TDD timeslots included in the plurality of periods to be larger than the numberof specific TDD time slots.

(11) The communication apparatus according to any one of (8) to (10), inwhich

the part of applications include at least one of an application thatgenerates a packet of I2C (Inter-Integrated Circuit) communication or anapplication that generates a packet of GPIO (General PurposeInput/Output) communication, and

the application designated in advance includes at least one of anapplication that generates a packet of SPI (Serial Peripheral Interface)communication or an application that generates a packet of OAM(Operation, Administration, Maintenance).

(12) The communication apparatus according to any one of (1) to (11), inwhich

the transmission control unit changes, for every one period, thepriority of the part of applications by one level, and makes, where thepriority has reached the lowest or the highest, the priority the highestor the lowest in the next period.

(13) The communication apparatus according to any one of (8) to (11), inwhich

the transmission control unit sets, on a basis of at least one of atransmission frequency or a signal amount of a serial signal generatedby each of the plurality of applications, whether to assign thededicated TDD time slot to the corresponding application or share thespecific TDD time slot with another application.

(14) The communication apparatus according to any one of (1) to (13),further including:

a plurality of encapsulators that is provided for each of the pluralityof applications, generates a packet including a serial signal generatedby the corresponding application, and outputs a ready signal indicatingwhether or not the packet has been generated; and

a frame construction unit that generates, on a basis of a plurality ofpackets generated by the plurality of encapsulators, a link frame to betransmitted to the communication partner device in the one period, inwhich

the frame construction unit includes a scheduler that manages thepriority of the specific TDD time slot and determines, on a basis of twoor more ready signals generated by two or more encapsulatorscorresponding to the part of applications, the application thattransmits a packet in the specific TDD time slot.

(15) The communication apparatus according to (14), in which

the frame construction unit includes

a plurality of container makers that generates a container including acontainer payload and a container header, the container payloadincluding a packet generated by each of the plurality of encapsulators,and

a multiplexer that selects, under control of the scheduler, a pluralityof containers generated by the plurality of container makers one by oneto generate the link frame.

(16) The communication apparatus according to (15), in which

the number of the plurality of container makers is the same as thenumber of TDD time slots in the one period.

(17) The communication apparatus according to any one of (1) to (13),further including:

a plurality of encapsulators that is provided for each of the pluralityof applications, generates a packet including a serial signal generatedby the corresponding application, and outputs a ready signal indicatingwhether or not the packet has been generated;

a packet selection unit that manages the priority of the specific TDDtime slot and selects, on a basis of two or more ready signals generatedby two or more encapsulators corresponding to the part of applications,a packet to be transmitted in the specific TDD time slot from two ormore packets generated by the two or more encapsulators; and

a frame construction unit that generates, on the basis of the packetselected by the packet selection unit and a packet corresponding to anapplication other than the part of applications of the plurality ofapplications, a link frame to be transmitted to the communicationpartner device in the one period, in which

the frame construction unit includes a scheduler that manages a packetto be transmitted in the plurality of TDD time slots in the one period.

(18) The communication apparatus according to (17), in which

the frame construction unit includes

a plurality of container makers that generates a container including acontainer payload and a container header corresponding to the containerpayload, the container payload including a packet selected by the packetselection unit and a packet corresponding to an application other thanthe part of applications of the plurality of applications, and

a multiplexer that selects, under control of the scheduler, a pluralityof containers generated by the plurality of container makers one by oneto generate the link frame.

(19) The communication apparatus according to (18), in which

the number of the plurality of container makers is less than the numberof TDD time slots in the one period.

(20) A communications system, including:

a first communication apparatus that transmits/and receives a packet byTDD (Time Division Duplex) via a predetermined communication protocol;and

a second communication apparatus, in which

the first communication apparatus includes

-   -   a communication unit that periodically transmits, with an        interval assigned by TDD (Time Division Duplex) being one TDD        time slot and a plurality of TDD time slots being one period, a        plurality of application packets corresponding to a plurality of        serial signals generated by a plurality of applications to a        communication partner device, and    -   a transmission control unit that changes, for every one period,        a priority of part of application packets corresponding to part        of two or more applications of the plurality of applications,        the part of application packets being transmitted in at least        one specific TDD time slot for transmitting the part of        application packets, the plurality of TDD time slots including        the at least one specific TDD time slot, and

the second communication apparatus includes a second communication unitthat receives a packet transmitted from the first communicationapparatus and periodically transmits a packet to the first communicationapparatus with the plurality of TDD time slots being the one period.

(21) A communication method, including:

periodically transmitting, with an interval assigned by TDD (TimeDivision Duplex) being one TDD time slot and a plurality of TDD timeslots being one period, a plurality of application packets correspondingto a plurality of serial signals generated by a plurality ofapplications to a communication partner device; and

changing, for every one period, a priority of part of applicationpackets corresponding to part of two or more applications of theplurality of applications, the part of application packets beingtransmitted in at least one specific TDD time slot for transmitting thepart of application packets, the plurality of TDD time slots includingthe at least one specific TDD time slot.

Aspects of the present disclosure are not limited to the above-mentionedindividual embodiments and include also various modifications that canbe conceived by those skilled in the art, and also the effects of thepresent disclosure are not limited to the above-mentioned content. Thatis, various additions, changes, and partial deletions can be madewithout departing from the conceptual idea and essence of the presentdisclosure derived from the content specified in the claims and theequivalents thereof.

What is claimed is:
 1. A communication apparatus, comprising: acommunication unit that periodically transmits, with an intervalassigned by TDD (Time Division Duplex) being one TDD time slot and aplurality of TDD time slots being one period, a plurality of applicationpackets corresponding to a plurality of serial signals generated by aplurality of applications to a communication partner device; and atransmission control unit that changes, for every one period, a priorityof part of application packets corresponding to part of two or moreapplications of the plurality of applications, the part of applicationpackets being transmitted in at least one specific TDD time slot fortransmitting the part of application packets, the plurality of TDD timeslots including the at least one specific TDD time slot.
 2. Thecommunication apparatus according to claim 1, wherein the transmissioncontrol unit changes, for every one period, the priority of the part ofapplication packets in a preset order or in accordance with user'sdesignation.
 3. The communication apparatus according to claim 1,wherein the transmission control unit changes, for every one period, thepriority of the part of application packets to be transmitted in thespecific TDD time slot in order.
 4. The communication apparatusaccording to claim 1, wherein the transmission control unitpreferentially transmits a packet corresponding to an application havinga higher priority in the specific TDD time slot.
 5. The communicationapparatus according to claim 1, wherein the transmission control unitchecks whether an application having a higher priority has prepared apacket to be transmitted in the specific TDD time slot, and checks, ifnot prepared, whether or not an application having the next highestpriority has prepared a packet to be transmitted in the specific TDDtime slot.
 6. The communication apparatus according to claim 5, whereinthe transmission control unit repeats processing of checking whether ornot a packet to be transmitted is prepared in descending order ofpriority until a packet that can be transmitted in the specific TDD timeslot is found.
 7. The communication apparatus according to claim 1,wherein the transmission control unit stops, where none of the part ofapplications have prepared a packet to be transmitted in the specificTDD time slot, transmitting a valid packet in the specific TDD timeslot.
 8. The communication apparatus according to claim 1, wherein thetransmission control unit causes the one period to include a dedicatedTDD time slot for transmitting a packet including a serial signalgenerated by an application designated in advance separately from thespecific TDD time slot.
 9. The communication apparatus according toclaim 8, wherein the application designated in advance is an applicationother than the part of applications of the plurality of applications.10. The communication apparatus according to claim 8, wherein thetransmission control unit increases the number of dedicated TDD timeslots included in the plurality of periods to be larger than the numberof specific TDD time slots.
 11. The communication apparatus according toclaim 8, wherein the part of applications include at least one of anapplication that generates a packet of I2C (Inter-Integrated Circuit)communication or an application that generates a packet of GPIO (GeneralPurpose Input/Output) communication, and the application designated inadvance includes at least one of an application that generates a packetof SPI (Serial Peripheral Interface) communication or an applicationthat generates a packet of OAM (Operation, Administration, Maintenance).12. The communication apparatus according to claim 1, wherein thetransmission control unit changes, for every one period, the priority ofthe part of applications by one level, and makes, where the priority hasreached the lowest or the highest, the priority the highest or thelowest in the next period.
 13. The communication apparatus according toclaim 8, wherein the transmission control unit sets, on a basis of atleast one of a transmission frequency or a signal amount of a serialsignal generated by each of the plurality of applications, whether toassign the dedicated TDD time slot to the corresponding application orshare the specific TDD time slot with another application.
 14. Thecommunication apparatus according to claim 1, further comprising: aplurality of encapsulators that is provided for each of the plurality ofapplications, generates a packet including a serial signal generated bythe corresponding application, and outputs a ready signal indicatingwhether or not the packet has been generated; and a frame constructionunit that generates, on a basis of a plurality of packets generated bythe plurality of encapsulators, a link frame to be transmitted to thecommunication partner device in the one period, wherein the frameconstruction unit includes a scheduler that manages the priority of thespecific TDD time slot and determines, on a basis of two or more readysignals generated by two or more encapsulators corresponding to the partof applications, the application that transmits a packet in the specificTDD time slot.
 15. The communication apparatus according to claim 14,wherein the frame construction unit includes a plurality of containermakers that generates a container including a container payload and acontainer header, the container payload including a packet generated byeach of the plurality of encapsulators, and a multiplexer that selects,under control of the scheduler, a plurality of containers generated bythe plurality of container makers one by one to generate the link frame.16. The communication apparatus according to claim 15, wherein thenumber of the plurality of container makers is the same as the number ofTDD time slots in the one period.
 17. The communication apparatusaccording to claim 1, further comprising: a plurality of encapsulatorsthat is provided for each of the plurality of applications, generates apacket including a serial signal generated by the correspondingapplication, and outputs a ready signal indicating whether or not thepacket has been generated; a packet selection unit that manages thepriority of the specific TDD time slot and selects, on a basis of two ormore ready signals generated by two or more encapsulators correspondingto the part of applications, a packet to be transmitted in the specificTDD time slot from two or more packets generated by the two or moreencapsulators; and a frame construction unit that generates, on thebasis of the packet selected by the packet selection unit and a packetcorresponding to an application other than the part of applications ofthe plurality of applications, a link frame to be transmitted to thecommunication partner device in the one period, wherein the frameconstruction unit includes a scheduler that manages a packet to betransmitted in the plurality of TDD time slots in the one period. 18.The communication apparatus according to claim 17, wherein the frameconstruction unit includes a plurality of container makers thatgenerates a container including a container payload and a containerheader corresponding to the container payload, the container payloadincluding a packet selected by the packet selection unit and a packetcorresponding to an application other than the part of applications ofthe plurality of applications, and a multiplexer that selects, undercontrol of the scheduler, a plurality of containers generated by theplurality of container makers one by one to generate the link frame. 19.The communication apparatus according to claim 18, wherein the number ofthe plurality of container makers is less than the number of TDD timeslots in the one period.
 20. A communications system, comprising: afirst communication apparatus that transmits/and receives a packet byTDD (Time Division Duplex) via a predetermined communication protocol;and a second communication apparatus, wherein the first communicationapparatus includes a communication unit that periodically transmits,with an interval assigned by TDD (Time Division Duplex) being one TDDtime slot and a plurality of TDD time slots being one period, aplurality of application packets corresponding to a plurality of serialsignals generated by a plurality of applications to a communicationpartner device, and a transmission control unit that changes, for everyone period, a priority of part of application packets corresponding topart of two or more applications of the plurality of applications, thepart of application packets being transmitted in at least one specificTDD time slot for transmitting the part of application packets, theplurality of TDD time slots including the at least one specific TDD timeslot, and the second communication apparatus includes a secondcommunication unit that receives a packet transmitted from the firstcommunication apparatus and periodically transmits a packet to the firstcommunication apparatus with the plurality of TDD time slots being theone period.
 21. A communication method, comprising: periodicallytransmitting, with an interval assigned by TDD (Time Division Duplex)being one TDD time slot and a plurality of TDD time slots being oneperiod, a plurality of application packets corresponding to a pluralityof serial signals generated by a plurality of applications to acommunication partner device; and changing, for every one period, apriority of part of application packets corresponding to part of two ormore applications of the plurality of applications, the part ofapplication packets being transmitted in at least one specific TDD timeslot for transmitting the part of application packets, the plurality ofTDD time slots including the at least one specific TDD time slot.